The present invention relates to a flat gasket with filter elements.
In order to fulfil the increased requirements with respect to cleanliness, there is an increased demand for the integration of filter elements in flat gaskets. The corresponding filter elements mainly serve for picking of impurities accrued during production as well as other residues circulate via the operational fluids, especially during the initial period of operation of an internal combustion engine or a vehicle.
Such flat gaskets are already known from the state of the art, e.g. from DE 200 19 040 U1 or DE 20 2010 006 768 U1. They are mainly used as gaskets for parts which guide water, air and/or oil. This can be gaskets in transmissions, cylinder head gaskets or other gaskets in internal combustion engines and especially gaskets in the exhaust line of internal combustion engines.
DE 20 2010 006 768 U1 teaches a flat gasket with a metallic mesh material being installed between two metallic layers. The mesh material extends between the metallic layers and also spans the area of the passage openings in the metallic layers. In and for these passage openings, the mesh layer acts as a filter. According to DE 20 2010 006 768 U1, the mesh material is not compressed in these filter areas, while it is compressed in the bridge areas where it is covered by the material of the metallic layers. This compression causes a transverse impermeability of the mesh material in the respective areas, whereas the non-compressed mesh material in the filter areas shows a reduced flow resistance for the fluid which passes through the passage openings in the metallic layers.
It is disadvantageous that the mesh material has to be compressed with a demanding process in the areas to be covered by the metallic layers, namely the sealing areas, while the filter areas have to be protected from any compression. Such a structured and local compression method is demanding and causes considerable cost of production.